The present invention relates to aircraft comprising foldable wings, rotational joints for use on such aircraft and to methods of assembly of such rotational joints and foldable aircraft wings.
There is a trend towards increasingly large passenger aircraft with higher performance efficiency (for example fuel burn reduction), for which it is desirable to have correspondingly large wing spans. However, the maximum aircraft span is effectively limited by airport operating rules which govern various clearances required when manoeuvring around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage).
In some suggested designs, aircraft are provided with wings that have a fixed wing and a wing tip device that is rotatably coupled to the tip of the fixed wing, by a rotational joint, to rotate to a ground configuration in which the span of the aircraft is reduced (compared to when the aircraft is configured for flight).
The wing tip device is coupled to drive shaft driven by an actuator, to rotate the wing tip device between the flight and ground configurations.
However, it has been found that if the actuator drive shaft and rotational joint are not aligned and/or are not oriented correctly relative to each other, this can result in undesirable forces being exerted on the actuator.
The present invention seeks to address or mitigate at least some of the above mentioned problems. Alternatively, or additionally, the present invention seeks to provide an improved rotational joint for a rotatable wing tip device. Alternatively, or additionally, the present invention seeks to provide an improved aircraft with a wing tip device that is rotatable relative to the fixed wing.